Completion apparatus and methods for use in hydrocarbon wells

ABSTRACT

The present invention provides a cement shoe assembly for use on a string of tubulars in a well. In one aspect of the invention, the cement shoe assembly includes a housing having a lower portion with an enlarged inside diameter and a drillable cement shoe disposed therein. The shoe includes a weakened portion of material adjacent the enlarged inside diameter portion of the housing and ensures that as a cutting tool passes through the housing, all portions of the cement shoe are removed from the enlarged inside diameter portion, leaving a connection surface clear of debris for a subsequent tubular string. When a smaller tubular is expanded into the enclosed diameter portion of the housing, a connection is made therebetween without enlarging the outer diameter of the housing.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.09/692,592, filed Oct. 19, 2000, now U.S. Pat. No. 6,845,820, which isherein incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention provides an apparatus and methods for use in ahydrocarbon wellbore. More particularly the invention provides apparatusand methods for completing hydrocarbon wells. Still more particularly,the invention provides a cement shoe assembly for use in monobore wells.

2. Background of the Related Art

In the drilling of a hydrocarbon well, the borehole is physically linedwith strings of pipe or tubulars (pipe or casing) to prevent the wallsof the borehole from collapsing and to provide a reliable path for wellproduction fluid, drilling mud and other fluids that are naturallypresent or that may be introduced into the well. Typically, after thewell is drilled to a new depth, the drill bit and drill string areremoved and a string of pipe is lowered into the well to a predeterminedposition whereby the top of the pipe is at about the same height as thebottom of the existing string of pipe (liner). Thereafter, with the newstring of pipe held in place either temporarily or with some mechanicalhanger, a column of cement is pumped into the pipe and forced to thebottom of the borehole where it flows out of the pipe and flows upwardsinto an annulus defined by the borehole and the pipe. The two principalfunctions of the cement between the pipe and the borehole are torestrict fluid movement between formations and to support the pipe.

To save time and money, apparatus to facilitate cementing are oftenlowered into the borehole along with a pipe to be cemented. Cementingapparatus typically includes a number of different components made up atthe surface prior to run-in. These include a tapered nose portionlocated at the downhole end of the pipe to facilitate insertion thereofinto the borehole. A check valve at least partially seals the end of thetubular and prevents entry of well fluid during run-in while permittingcement to subsequently flow outwards. The same valve or another valve orplug typically located in a baffle collar above the cementing toolprevents the cement from back flowing into the pipe. Components of thecementing apparatus are made of fiberglass, plastic, or other disposablematerial, that, like cement remaining in the pipe, can be drilled whenthe cementing is complete and the borehole is drilled to a new depth.

Historically, each section of pipe inserted to line a borehole wasnecessarily smaller in diameter than the section of pipe previouslyinserted. In this manner, a wellbore was formed of sequential strings ofpipe of an ever-decreasing inner and outer diameter. Recently, methodsand apparatus for expanding the diameter of pipe in a wellbore haveadvanced to the point where it has become commercially feasible toutilize the technology. This has led to the idea of monobore wellswherein through the expansion of tubulars in the wellbore, the wellboreremains at about the same diameter throughout its length. The advantagesof the monobore well are obvious. The tubulars lining the borehole, andtherefore the possible path for fluid in and out of the well remainsconsistent regardless of well depth. Additionally, tools and otherdevices can more easily be run into the well without regard for thesmaller diameters of tubulars encountered on the way to the bottom ofthe wellbore.

In a monobore well, a first string of tubulars is inserted into thewellbore and cemented therein in a conventional manner. Thereafter, astring of tubulars having a smaller diameter is inserted into thewellbore as in prior art methods. However, after insertion into thewellbore the second string of tubulars is expanded to approximately thesame inner and outer diameter as the first string. The strings can beconnected together by use of a conventional hanger or, more typically,the smaller tubing is simply expanded into the interior of the largerdiameter tubing thereabove in an area where the pipes overlap.

With the advent of monobore wells, certain problems have arisen. Oneproblem relates to the expansion of the smaller tubular into the largertubular to form the connection therebetween. Current methods ofexpanding tubulars in a wellbore to create a connection between tubularsrequires the application of a radial force to the interior of thesmaller tubular and expanding its diameter out until the larger tubularis itself pushed passed its elastic limits. The result is a connectionhaving an outer diameter greater than the original outer diameter of thelarger tubular. While the increase in the outer diameter is minimal incomparison to the overall diameter, there are instances where expandingthe diameter of the larger pipe is difficult or impossible. For example,in the completion of a monobore well, the upper string of tubulars ispreferably cemented into place before the next string of tubulars islowered into the well and its diameter expanded. Because the annulararea between the outside of the larger pipe and the borehole therearoundis filled with cured cement, the diameter of the larger pipe cannotexpand past its original shape.

Therefore, a need exists for a connection means between two tubulars ina wellbore whereby a smaller tubular can be expanded into a largertubular without the need for expanding the outer diameter of the largertubular during the expansion process. There is a further need for anapparatus for running a string of pipe into a wellbore including acement shoe whereby, a another string of tubular can be subsequentlyexpanded into the first string without increasing the outer diameter ofthe larger pipe. There is yet a further need for a cement shoe assemblywhich can be run into a well at the end of a string of tubulars andwhich can subsequently be drilled out leaving a portion of a cement shoehousing clear for connection to another smaller tubular by expansionmeans.

SUMMARY OF THE INVENTION

The present invention provides a cement shoe assembly for use on astring of tubulars in a well. In one aspect of the invention, the cementshoe assembly includes a housing having a lower portion with an enlargedinside diameter and a drillable cement shoe portion disposed therein.The shoe includes a weakened portion of material adjacent the enlargedinside diameter portion of the housing and ensures that as a cuttingtool passes through the housing, all portions of the cement shoe areremoved from the enlarged inside diameter portion, leaving a connectionsurface clear of debris for a subsequent tubular string. When a smallertubular is expanded into the enclosed diameter portion of the housing, aconnection is made therebetween without enlarging the outer diameter ofthe housing. In another aspect of the invention, the cement shoeincludes a longitudinal bore providing a passageway for cement and otherfluids with composite material therearound. Radial formations extendfrom the outer surface of the longitudinal bore to the inside surface ofthe enlarged inner diameter portion of the body, thereby assuring thatas a drilling tool passes through the body, any material along thesurface-of the enlarged inside diameter portion of the housing will fallaway, leaving the portion free of debris.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features, advantages andobjects of the present invention are attained and can be understood indetail, a more particular description of the invention, brieflysummarized above, may be had by reference to the embodiments thereofwhich are illustrated in the appended drawings.

It is to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1 is a side view in section of the cement shoe assembly of thepresent invention.

FIG. 2 is a more detailed section view of the conical nose portion ofthe cement shoe assembly shown in FIG. 1.

FIG. 3 is a downward, cross-sectional view of the cement shoe assemblyof FIG. 1 taken through a line 3—3 of FIG. 2.

FIG. 4 is a section view of a wellbore showing the housing of the cementshoe assembly cemented in place and a second tubular therebelow beingexpanded into the housing with an expansion tool.

FIG. 5 is a section view of the wellbore of FIG. 4, showing a completedconnection formed between the housing of the cement shoe assembly andthe second tubular.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 is a section view of a cement shoe assembly 100 of the presentinvention. The assembly 100 is typically disposed at the end of a stringof tubulars that is run into a well and cemented therein to isolate thewellbore from the formation therearound. The assembly 100 is preferablyconnected to a tubular 101 by a threaded connection 102 formedtherebetween. The cement shoe assembly 100 includes a housing 110 and adrillable shoe portion 120 disposed within the housing. The drillableshoe portion 120 includes a longitudinal bore 123 extending through thecenter of the cement shoe and providing a fluid path for cement and wellfluids. At an upper end, the bore 123 communicates with the tubular 101.Therebelow, a biased, one way valve 150 is disposed in the bore 123permitting fluid to enter from the well surface but preventing wellfluids from passing from the wellbore into tubular 101. In theembodiment shown, a spring 151 biases the valve 150 in a closedposition. Adjacent valve 150, an annular area 121 defined between thebore and the housing 110 is filled with concrete to stabilize the bore123. The housing 110 surrounding the concrete is equipped with upsets152 to hold the concrete in place and prevent axial movement thereof.Lining the bore 123 between the valve 150 and a conical nose portion 130is a tubular member 131. Adjacent the tubular member 131, an annulararea 132 between the tubular member and the housing 110 is filled withsand or some other aggregate. The purpose of the sand is to support thetubular member 131 in the center of the bore 123 and to preventmigration of cement from the bore 123 to the well of the housing 110through pressure equalization ports 139 formed in tubular member 131.

At a lower end of the assembly 100 is conical nose portion 130. Theconical nose portion serves to direct fluid into and out of the assembly100. Additionally, the offset, conical shape of the nose portion 130aids in run-in of the assembly by facilitating the passage of theassembly 100 through the borehole. The construction and the shape ofnose portion 130 is illustrated in detail in FIG. 2, an enlarged,section view thereof. At an upper end 136 the nose portion fits intohousing 110 and is attached thereto with a threaded connection 134. Acentral bore 143 of the nose portion 130 is aligned with longitudinalbore 123 of the shoe portion 120. The nose portion 130 also includes atleast one side port 133 for the passage of cement from the longitudinalbore 123 to the borehole (not shown). The nose portion 130 isconstructed of drillable material having wear resistant, drillablecharacteristics. Fiberglass or some other composite material istypically used to form the conical nose portion 130. Located at an outeredge of the nose portion 130, at a point where the nose portion meetsthe edge of the housing 110, is a groove 171 formed around the perimeternose portion. The groove 171 is constructed and arranged to ensure thatthe lower nose portion 135 falls away from the housing 110 as the shoeportion 120 and the upper nose portion 136 is drilled in the wellbore aswill be described herein.

Also included in the upper portion 136 of the conical nose portion 130are a plurality of radially extending formations 140 originating at aninner edge 137 of the housing 110 and extending inward to terminateadjacent the tubular member 131. In the preferred embodiment, theformations 140 are voids formed in the composite material of the conicalnose portion. FIG. 3 is a section view of the nose portion of theassembly taken along a line 3—3 of FIG. 2. FIG. 2 illustrates therelative height of the formations 140 and FIG. 3 illustrates the widthand length of each formation 140. The purpose of the formations is toensure that the outermost portions of the upper nose portion 136 fallaway from the housing 110 as the shoe portion is drilled as will beexplained herein.

Visible specifically in FIGS. 1, 4 and 5, the outer housing 110 of theassembly is a two piece housing with a threaded connection 134 betweenan upper 138 and lower 161 portions. In the embodiment shown, the upperportion 138 of the housing 110 has approximately the same outer diameteras the tubular 101 thereabove. The lower portion 161 of the housingincludes an area of increased wall thickness 157 terminating in an areaof the housing 160 having an enlarged inner diameter. The enlargedinside diameter area 160 is designed to provide a non-expanding matingsurface for the upper portion of a tubular when the tubular is expandedinto housing 110 as described herein.

In the completion of a well utilizing the cement shoe assembly of thepresent invention, an initial or subsequent section of borehole isdrilled to a predetermined depth in the earth. Thereafter, a string oftubular is run into the new borehole with the cement shoe assembly 100disposed at a lower end thereof. With the tubular string fixed in thewellbore and the cement shoe assembly 100 near the bottom of theborehole, cement is injected into the wellbore with the tubular stringproviding a fluid path for the cement. When the flowing cement reachescement shoe assembly 100, it passes through one-way valve 150, throughlongitudinal bore 123 and exits the central bore 143 of the conical noseportion 130 as well as side ports 133. Upon reaching the bottom of theborehole, the cement is then forced up an annular area formed betweenthe outer surface of the housing 110 and the borehole therearound (notshown). A column of fluid is then pumped into the tubular string afterthe cement to ensure that most of the cement exits the lower end of thecement shoe assembly 100. Thereafter, the cement is allowed to cure andsubsequently, a drilling tool is run into the wellbore inside of thetubular string and the drillable shoe portion 120 and conical noseportion 130 are drilled up and destroyed, leaving only the housing 110.Thereafter, a new length of borehole is drilled and subsequently linedwith another tubular string. The upper portion of the new string oftubular is subsequently expanded into the enlarged inside diameterportion 160 of housing 110 of the cement shoe assembly 100.

In a conventional cement shoe, the inside diameter of the cement shoehousing is only slightly larger than the outer diameter of a drillingtool used to drill the drillable cement shoe portion 120. This ensuresthat the material making up the cement shoe is removed. In the presentinvention, as illustrated in the Figures, the housing 110 of the cementshoe assembly is not a uniform inside diameter but includes largerinside diameter area 160. As previously explained, the larger insidediameter area 160 permits the expansion of a tubular into the housingwithout expanding the outside diameter of the housing 110. In thismanner a connection may be made between the housing and another piece oftubular, even when the housing is cemented into place in the wellboreand its outer diameter cannot be expanded.

In order to ensure that all portions of the shoe portion 120 and conicalnose portion 130 fall free of housing 110 in the enlarged insidediameter area 160, the formations 140 in the upper portion of theconical nose portion are designed to remove all radial support for anymaterial left between the drill and the wall of the housing 110 when thedrilling tool passes through the housing 110. Considering FIG. 1, adrilling tool, when passing through the upper portion 138 of the housing110, will contact, break-up and loosen all material and components inthe upper portion 138 of the housing. Debris from the material andcomponents is carried to the surface by circulating fluids. Likewise, asthe drilling tool passes from the housing 110 to the conical portion 130it will intersect groove 171 and the lower conical portion 135 will bedislodged from housing 110. However, as the cutting tool passes throughthe enlarged inside diameter portion 160 of housing 110, some materialmaking up the upper portion 136 of the conical nose portion will not bedirectly contacted by the drilling tool. As is visible in FIG. 3,formations 140 remove any radial support of composite material whichmight remain in a ring-like shape after the drilling tool passes throughthe upper portion 136 of the conical nose portion 130.

As described above, after the drillable components and material makingup the shoe portion 120 are drilled up, the larger inside diameter area160 of the housing remains as a mating surface for the expansion of atubular having a smaller diameter. FIG. 4 is a section view of awellbore illustrating housing 110 cemented into place in a borehole 450and a tubular 420 therebelow being expanded into the larger insidediameter area 160 of housing 110. Typically, after a new string oftubular is fixed in the wellbore, an expansion tool 400 will be run intothe well on a run-in string of tubular 406 and used to enlarge the innerand outer diameter of the tubular string to the size of the tubularstring thereabove. FIG. 4 illustrates one expansion tool 400 typicallyused to expand a tubular string in a “bottom-up” fashion.

The expansion tool 400 operates with pressurized fluid supplied throughrun-in string 406. The expansion tool 400 includes a body 402 which ishollow and generally tubular with a connector 404 for connection to therun-in string 406. The body 402 includes at least two recesses 414 tohold a respective roller 416. Each of the mutually identical rollers 416is near-cylindrical and slightly barreled. Each of the rollers 416 ismounted by means of a bearing (not shown) at each end of the respectiveroller for rotation about a respective rotation axis which is parallelto the longitudinal axis of the expansion tool 400 and radially offsettherefrom. The inner end of a piston (not shown) is exposed to thepressure of fluid within the hollow core of the tool 400 and the pistonsserve to actuate or urge the rollers 416 against the inside wall of atubular therearound. In FIG. 4, the expansion tool 400 is shown in anactuated position and is expanding the diameter of a tubular into a boredefined by the larger inside diameter area 160 of housing 110.Typically, the expansion tool 400 rotates as the rollers are actuatedand the tool is urged upwards in the wellbore. In this manner, theexpansion tool can be used to enlarge the diameter of a tubularcircumferentially to a uniform size and to a predetermined length in thewellbore. FIG. 5 illustrates a completed connection between the enlargeddiameter area 160 of housing 110 and the tubular 420. As illustrated,the inside and outside diameter of the tubular 420 has been increased asthe tubular is expanded past its elastic limits. However, the enlargedinside diameter area 160 of housing 110 has not expanded in diameter. Inthis manner, the tubular 420 is successfully affixed to the housing 110without expanding the diameter of the housing. Additionally, the insidediameter of the housing 110 and the tubular 420 are substantially thesame.

The connection arrangement disclosed herein and shown in FIGS. 4 and 5is not limited to use with a cement shoe assembly and can be used tojoin tubulars at any location downhole when a connection betweentubulars is desired without expanding the outer diameter of the largertubular. For example, the apparatus and method can be utilized anytimecement, formations or any other material surrounding the outer tubularmake it difficult or impossible to use an expansion technique requiringthe expansion of the larger tubular. Additionally, the methods andapparatus disclosed and claimed herein can be used in any well and arenot necessarily limited to use in a hydrocarbon well.

While the foregoing is directed to the preferred embodiment of thepresent invention, other and further embodiments of the invention may bedevised without departing from the basic scope thereof, and the scopethereof is determined by the claims that follow.

1. A method of isolating an annular area in a wellbore, comprising:coupling an isolation member to a string of casing having an enlargedinner diameter portion at a lowermost end thereof, thereby isolating anannular area formed between an outer surface of the isolation member andat least the enlarged inner diameter portion of the string of casing;and placing the string of casing into a wellbore.
 2. The method of claim1, wherein the string of casing has a uniform outer diameter.
 3. Themethod of claim 1, further comprising removing the isolation member. 4.The method of claim 3, further comprising disposing a second string ofcasing into the wellbore and expanding a portion of the second stringinto the enlarged inner diameter portion.
 5. The method of claim 1,further comprising drilling out the isolation member.
 6. The method ofclaim 1, further comprising filling the annular area with an aggregate.7. A method of preventing accumulation of unwanted materials in anannular area in a wellbore, comprising: coupling an isolation memberinside a portion of a first string of casing to form the annular area;running the first string of casing having an enlarged inner diameterportion at an end into a wellbore; disposing a second string of casinginto the first string of casing; and expanding the second string ofcasing into the enlarged inner diameter portion.
 8. The method of claim7, further comprising removing the isolation member.
 9. The method ofclaim 7, further comprising drilling out the isolation member.
 10. Themethod of claim 7, wherein the annular area extends at least the lengthof the enlarged inner diameter potion.
 11. The method of claim 7,wherein the first string of casing has a uniform outer diameter.
 12. Acement shoe assembly, comprising: a tubular housing disposed at an endof a tubular string, the housing having a first inner diameter portionand an enlarged inner diameter portion at a lowermost end of thehousing; an isolation member disposed in the housing at least adjacentthe enlarged inner diameter portion; and a valve that selectivelypermits fluid passage through the cement shoe assembly.
 13. The assemblyof claim 12, wherein an annular space is formed between the isolationmember and a portion of the tubular housing.
 14. The assembly of claim13, wherein the annular space extends at least substantially the lengthof the enlarged inner diameter portion.
 15. The assembly of claim 13,wherein the annular space is filled with an aggregate.
 16. The assemblyof claim 12, wherein the isolation member prevents migration of cementfrom a bore defined by the isolation member to the enlarged innerdiameter portion.
 17. The assembly of claim 12, further comprising anose portion proximate the enlarged inner diameter portion, wherein theisolation member extends between the nose portion and the valve.
 18. Theassembly of claim 12, wherein an outer diameter of the tubular housingis uniform.
 19. The assembly of claim 12, wherein the isolation memberis drillable.
 20. A well completion method, comprising: running incasing having a first inside diameter; providing a shoe adjacent thelower end of said casing; running a tubular string through said casinguntil the upper end of the tubular string is adjacent said shoe; andexpanding at least a portion of said tubular string into supportingengagement with said shoe so that a second inside diameter of saidtubular string, after expansion, in said shoe is at least as large assaid first inside diameter of said casing.
 21. The method of claim 20,further comprising providing an initial third inside diameter in saidshoe that is smaller than said first diameter in said casing.
 22. Themethod of claim 20, further comprising providing an initial third insidediameter in said shoe that is larger than said first diameter in saidcasing.
 23. The method of claim 20, further comprising providing aninitial third inside diameter in said shoe that is substantially thesame as said first diameter in said casing.
 24. The method of claim 23,further comprising expanding said tubular sting and said shoe in asingle trip into the wellbore.
 25. The method of claim 20, furthercomprising providing an initial third inside diameter in said shoe thatis altered downhole.
 26. The method of claim 25, further comprisingincreasing said third diameter by removing portions of said shoe. 27.The method of claim 26, further comprising using a mill or drill bit toremove portions of said shoe downhole.
 28. The method of claim 25,further comprising providing a sleeve in said shoe; removing the sleevedownhole.
 29. The method of claim 28, further comprising mechanicallyremoving said sleeve from said shoe.
 30. A shoe assembly for use with acasing string, comprising: a housing connected to a lower end of thecasing string, the housing having an enlarged inner diameter portion ata lowermost end of the housing; and a detachable isolation portiondisposed in the housing, the detachable isolation portion in fluidcommunication with an inner diameter of the casing string, wherein thedetachable isolation portion substantially blocks at least a portion ofthe enlarged inner diameter from fluid communication with the innerdiameter of the casing string.